Not applicable.
Not applicable.
1. Field of Invention
This invention relates to a method and device for determining the level of cleanliness in a pipe, conduit and the like. Specifically, the invention describes a target inserter for use with high-pressure high-velocity fluids (steam, liquid, air or similar cleaning fluids).
2. Related Art
Piping, conduits, vessels and similar structures are used in a variety of manners. Typically, such conduits are used to transport fluid materials, such as hydrocarbons, brine, and other liquids used in chemical and petrochemical processes. Similarly, such conduits may be used to transport fuels, including gas and liquid hydrocarbons. Conduits in other applications include those used to provide power steam in turbines. Typically, over time the interior surfaces of such piping frequently become coated with scale and other buildup of the transported material or its by-products. These deposits on the walls of the interior of the conduits pose a variety of problems, depending on the conduit and its use. For example, debris such as scale in a steam line may become dislodged, causing severe damage to steam turbine blades when struck by the entrained debris in the high velocity steam line. Buildup on the walls of piping in a heat exchanger reduce the efficiency in the heat transfer, including irregular heat transfer that may result in inefficient chemical reactions. Buildup on the walls of feedstock or fuel line in a petrochemical process may result in turbulence or blockage in the line, reducing the efficiency of the process until it is forced to shut down.
In a petrochemical or similar processing unit, cleaning of the lines cannot be accomplished while the unit is in operation. The unit must be shut down for such maintenance, referred to typically as a xe2x80x9cturnaroundxe2x80x9d. Normally closed loop systems are drained of their contents, purged if necessary, and cleaned out. A common method of cleaning out the lines is with high velocity steam. High temperature steam is flushed through the lines at high velocity, mechanically breaking off and flushing the built-up material on the wall interior. Cavitation often occurs as the high-velocity steam passes through the conduit, thus aiding in the breaking up of the build-up slag away from the vessel walls.
In the prior art, such as described by Bloch in U.S. Pat. No. 4,853,014, low-pressure high-velocity steam is used for interior cleaning of pipes. Pressure is built up in a boiler, and then released through the lines to be cleaned. The lines are then allowed to cool while steam pressure is built up again in the boiler. This blow cycle is repeated until the line is clean. To determine if the steam (and therefore the line) is clean, a piece of soft metal called a target is supported across the interior of the terminal portion of the line. The target is inserted into the line (typically between blow cycles), steam is blown through the line, and the target then removed. Pits in the metal target are caused by debris from the line striking the metal. These pits are counted to quantify the level of cleanliness of the line. When the line is still xe2x80x9cdirtyxe2x80x9d, numerous pits are observed. As the line becomes cleaner, there are fewer small debris particles being pushed by the steam, and thus there are fewer pits in the target. The steam is then vented out the line through an expansion chamber, into which Bloch introduces a decelerating mist for noise control. While this method takes advantage of the flushing and cavitational forces provided by steam at near sonic velocity, being at low pressure requires a high volume of water to adequately flush out the line. Further, target insertion/removal must be performed at low pressure, typically between blow cycles, due to the prior art design limitations of the target inserter. Finally, the steam can only be used in a single unit, since there is inadequate pressure to pipe the steam to a second unit to clean it as well.
A preferred method of cleaning pipes, conduits and like devices is to use a high-pressure high-velocity gas stream, typically steam. While the term xe2x80x9csteamxe2x80x9d will be used throughout the description of the prior art and this invention, it is understood that xe2x80x9csteamxe2x80x9d is to encompass all similar gas streams used in the context of pressure cleaning.
Using a high-pressure gas stream offers several advantages over low-pressure. First, since most systems being cleaned normally operate at high pressure, they respond best to a high-pressure cleaning gas stream. Such systems often have bends and recesses in their interior structure of the conduits. As such, the normal fluid traveling through the piping hits and impinges on areas within the conduit that may be restricted. A low-pressure gas stream will not invade such spaces, but will pass over these areas. Therefore, a high-pressure gas stream that mimics the pressure and characteristics of the material within the conduit during normal operation will provide better cleaning access to all areas within the conduit. Second, low-pressure gas streams rely heavily on the force of relatively high volume of water to flush out the conduit being cleaned. The water used is typically demineralized, and is relatively expensive compared to untreated water. Further, this high volume of water must be treated after being flushed through the conduit, which often contains hazardous materials. Treatment of this effluent water is often expensive and resource consuming. Finally, high-pressure steam can be used to clean more than one unit. By connecting more than one unit of conduits with a temporary connection line, steam used to clean the first unit can continue through the temporary connection to flush through the second unit.
While the advantages of using high-pressure high-velocity steam are clear, such steam has not been used due to technical and safety problems associated with the target. As described above, a target is used to determine the cleanliness of the conduit by determining the cleanliness of the steam. By determining the cleanliness of the steam, it is assumed that the interior of the conduit being cleaning is analogously clean, having had all friable and loose scale knocked off by the steam. When using the same steam to clean a second unit that was used in a first unit (using temporary connection piping as described above), a method and device are needed to determine the cleanliness of the first unit as well as the second unit. If the target is only placed at the exit of the second unit piping, the source of debris causing pitting on the target is unknown, since it could come from the first unit or the second unit. Thus a target inserter between the first unit and second unit is needed to measure the cleanliness of the first unit. The cleanliness of the second unit is then determined by subtracting the number of pits from the first unit""s target from the number of pits from the second unit""s target.
It would therefore be useful improvement of the prior art of target inserters to be able to function in a high-pressure high-velocity steam environment while the cleaning system is still under high pressure.
Accordingly, the objectives of this invention are to provide, inter alia, a new and improved target inserter for use in determining the cleanliness of a pipe, conduit and like device being cleaned by a high-pressure high-velocity gas stream cleaning system. These objectives include having a device and system that:
operates at high pressure;
utilizes standard metal targets and target rods;
can be remotely operated for increased safety; and
connects to standard pipe flanges and valves.
These objectives are addressed by the structure and use of the inventive device. Other objects of the invention will become apparent from time to time throughout the specification hereinafter disclosed.